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arXiv · 1709.01013

Magnetic Excitations in the Ground State of $\mathrm{Yb_2Ti_2O_7}$

Viviane Pecanha-Antonio·Erxi Feng·Yixi Su·Vladimir Pomjakushin·Franz Demmel·Lieh-Jeng Chang·Robert J. Aldus·Yinguo Xiao·Martin R. Lees·Thomas Brückel
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Abstract

We report an extensive study on the zero field ground state of a powder sample of the pyrochlore $\mathrm{Yb_2Ti_2O_7}$. A sharp heat capacity anomaly that labels a low temperature phase transition in this material is observed at 280 mK. Neutron diffraction shows that a \emph{quasi-collinear} ferromagnetic order develops below $T_\mathrm{c}$ with a magnetic moment of $0.87(2)μ_\mathrm{B}$. High resolution inelastic neutron scattering measurements show, below the phase transition temperature, sharp gapped low-lying magnetic excitations coexisting with a remnant quasielastic contribution likely associated with persistent spin fluctuations. Moreover, a broad inelastic continuum of excitations at $\sim0.6$ meV is observed from the lowest measured temperature up to at least 2.5 K. At 10 K, the continuum has vanished and a broad quasielastic conventional paramagnetic scattering takes place at the observed energy range. Finally, we show that the exchange parameters obtained within the framework of linear spin-wave theory do not accurately describe the observed zero field inelastic neutron scattering data.

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Viviane Pecanha-Antonio, Erxi Feng, Yixi Su, Vladimir Pomjakushin, Franz Demmel, Lieh-Jeng Chang, Robert J. Aldus, Yinguo Xiao, Martin R. Lees, Thomas Brückel. 2017-12-01. Magnetic Excitations in the Ground State of $\mathrm{Yb_2Ti_2O_7}$. https://doi.org/10.1103/physrevb.96.214415

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